Method of oil temperature control



SePt- 27 l9493 L. T. MILLER 2,483,29l

METHOD 0F OIL TEMPERATURE CONTROL Original Filed Oct. 7. 1941 4 Sheets-Sheet l f Kfz/ff maf IN VEN TOR. LESLIE 7.' M/L'LER Sept. 27 1949. I q ,r-r, MlLLER 2,483,291,

METHOD OF OIL TEMPERATURE GOHTROL original Filed oei. 7. 1941 I 4 sheets-sheet a FIG. 4

i? l 4 I7/ Y/ ///M \1 i w f V/ n E y A .9 a F FIG. 5

ATTORNEY Sept 27,1949. L. T. MILLER I 2,483,291

l METHOD oF o1L TEMPERATURE coNTRoL Original Filed 0G12.- 7, 1941 v 4 Sheets-Sheet 3 (INVENTOR. ESL/E r. /u/LLER ATTORNEY Sept. 27, `1949. l L. 1'. MILLER METHOD oF IL TEMPEBATRE CONTROL Original Filed Oct. 7, 1941 4 Sheets-Sheet 4 INVENTOR. LESLIE KAI/LER ATTURNEY exchanger.

Patented sept. 27, 1949l UNITED STATES VPATENT OFFICE METHOD OF OIL TEMPERATURE CONTROL Leslie T. Miller, stoneleigh, Ma., assignmto The Glenn L. Martin Company, Middle River, Md., a corporation of Maryland Original application October 7, 1941, Serial lilo.

Divided and this application Noveml ber 21, 1944, sername. 564,528

This application is a division of application Serial No. 414,095, led October 7, 1941, now Patent No. 2,374,639, dated April 24, 1945. In operating internal combustion engines, especially aircraft engines, it is essential that the temperature of the lubricating oil in the engine be maintained at a relatively constant temperature for optimum engine operation. Not only must the oil be quickly brought up to this desired temperature, but throughout the flight of the aircraft, it must be maintained and not permitted to become either too hot or too cool.

Another important feature of the present system and apparatus thereof is the substantially complete removal of excessive oil pressures which are prevalent when the oil is cold and the engine is rst started up. In modern aircraft, Warm-up chambers and oil coolers have been proposed,'but due to the inherent construction of conventional oil coolers by which attempts have been made to maintain constant oil conditions, these coolers must not be subjected to pressures in excess of their structural limits. 'Ihe conventional oil coolers such as are used in modern aircraft comprise primary and secondary heat exchange sections or cores, the structure of which is necessarily of thin material to promote more efiicient heat exchange. Maximum cooling of the-oil is obtained by directing the oil through both sections of the heat exchanger. A partial cooling of the oil is obtained by causing the oil to iow through a small or secondary portion of the heat This small portion of the heat exchanger, used for limited cooling of the oil, is termed, in the industry, an oil cooler warming section or a warm-up section ofthe oil cooler.

. By this is meant that only this small portion of the heat exchanger is used for limited cooling of the oil during the process of warming up the engine from a cold start. In this application, we shall refer to the main section of the heat exchanger as the primary heat exchanger and the section used during the warming period as a secondary heat exchanger. It is to be understood from the above description that the primary ancl secondary heat exchangers may be portions of a single commercial heat exchange unit.

1 claim. (cl. 23e-s4) These structural limits great sacrifice as to weight. Heretofore, the pressurescreated by the cold oil have oftentimes burst these conventional types of coolers and resulted in great danger to the aircraft and crew.

Among the objects andv advantages of the present method is the complete elimination of these hazards and the precise regulation and control of the oil temperature nnder all conditions, including initial starting, preliminary'` warm-up and actual flight. l

It has been previously proposed lto control oil temperature by a valve located at the inlet to the engine, this valve regulating the owto the oil cooler or to' a by-.pass line to the oil tank. With such a valve, there is a considerable quantity of oil in the circuit between the oil cooler and the valve, including, as it does, the amount offoil in the tank; thus, it should be noted that this quantity of oil must pass through the valve before it can operate to change the amount of cooling to reduce the oil temperature. This lag results in uneven tempera-ture and may result in a hazardous condition when the -heat input from the engine to the oil is suddenly increased tremendously due to a change of operating conditions. By placing a thermostatic element immediately .adjacent to the oil cooler, and preferably bolted thereto, this time lag is decreased, and the necessity for an additional line back to the oil tank is eliminated.

Thisv invention contemplates the relieving of dangerous pressures after the engine has beenf rst started, the warming up of the oil returning from the engine to bring it up to operating temperature, and the cooling ofthe oil should it attempt to exceed the desired temperature. In addition, the system and apparatus permitthe automatic warming ofthe oil if during night the cooler lowers its 'temperature to a degree' below that desired for operation.

In the drawings:

Figure 1 is a diagrammatical ylayout of the'system showing a means of controlling the ow of oil during the diiferent periods of operation.

Figure 2 is a basically similar system to Figure 1 with means for circulating the'oil through the secondary heat exchanger and through both the secondary heat exchanger and primary heat ex- ,changer ata higher temperature'.

Figure 3 is also a similar'system to that of -Figure 1 but having a pressure relief valve therein for further protection' against excessive pressures. t I

Fig. 4 is a vertical cross section through a temcan be increased but 'at perature regulating valve of the reciprocating type used to control these several conditions in a system as shown in Fig. 1.

' Figs. 5 and 6 are similar to Fig. 4 but showing the sliding regulating valve in varying positions.

Figs. 10, 11 and 12 are vertical cross sections of the modied sliding type of control valve used in combination with the dual return lubricating system shown in Figs. '1, 8 and 9. 1

Figs. 13, 14 and 15 show a further modiiied form of temperature controlled valve similar in operation to the valve shown in Figs. 4, and 6 but adapted to be rotated by the oil temperature.

Figure 13 is a vertical cross section through this modied valve, while Figures 14 and 15 are vertical, transverse sections taken on lines I4-I4 and I5-'I5, respectively, of Figure 13.

Figures 16 and 17 show a further modified form of rotary valve corresponding to the valve illustrated in Figures 1Q to 12, inclusive, but us- .ing a rotary valve plug instead of a sliding sleeve.

Figure 16 is a vertical, longitudinal cross section of the modified form of rotary valve.

Figure 1'7 is a vertical, transverse section taken on line II-I'I of Figure 16.

valve I permits the cold oil to enterport A and freely pass out through port B through conduit 23 back into the valve through vport C and be discharged therefrom through port-G into the reservoir Il). Thus, during the initial start-up period when the oil is cold, it is permitted to pass through the system without undue restriction and without building up substantial pressures to thus completely eliminate its passage through either primary core I9 or secondary heat exchanger 20.

As the oil temperature starts to rise due to heat absorbed thereby from the engine I4, the temperature responsive element 4 moves the valve sleeve 3 to close oi ports B and C and open ports D and E. When this occurs, the oil enters port A and ows out through port D into conduit 2| and passes through the secondary heat exchanger 20, which in practice is combined with the oil heat exchanger core I9 and forms in effect an oil heat exchanger assembly, and

thence through conduit 25 to port E to be dis and 25 to port E from whence it passes through the open tubular portion of the valve and outlet G.-

Referring now to Figures 1, 4, 5 and 6. of the` drawings, numeral I denotes a multi-port thermostatically controlled valve comprising an outer casing 2 and an inner multi-ported reciprocating sleeve, or cylinder, 3 adapted to receive the movement from a thermostatic coil 4 attached to the inner sleeve 3 through linkage mechanism 5. As shown, the oil outlet port G discharges into a conduit 9 leading toan oil tank, or reservoir, I0 from thence it passes through conduit II to pump' I2 and conduit I3 into an engine I4, from the engine back to the inlet port A of the control valve I through conduit I5.

A primary heat exchanger I9 of suitable capacityland thermal characteristics is joined to the control valveI and port F thereof b y conduit I'I, while the opposite side of the primary heat exchanger is provided with conduit I8 in communication with a secondary heat exchanger 20 having a conduit 2I leading to,port D. The

conduit I8 is also joined to the control valve and port E thereof through conduit 25. A by'- The system illustrated in Figure 2 is quite similar to that described in explaining the operation ofl Figure l. The major diierence and furtherance of the present novel lubricating system shown in this gure is the means by which the primary heat exchanger and secondary heat exchanger may be connected to the control valve in such a manner that the oil may selectively flow through the secondary section at one temperature and through both the secondary section and primary section at a higher temperature.

With the arrangement of Figure 2, the primary heat exchanger I9 is joined to the control valve I and port F thereof by conduit I1, while the other side of the primary heat exchanger is connected by conduit 24 leading to the secondary unit 20 and thence through conduit 25 to port E. The conduit 24 also communicates with the through these ports will now be described in detail.

. When starting up, the engine I4 is cold as -is the oil supply in the system, including the tank I0. It will be obvious that if this low viscosity cold oil is permitted to circulate through the primary heat exchanger I9, or through secondary heat exchanger 20, the resistance built up in the system will be of such magnitude that there is great danger of rupturing the core of the heat exchanger. Consequently, due to the control valve port D by jointure with conduit 26.

In operation, as the oil temperature in the system starts to rise due to heat absorption from the initial operating period of the engine I4, the temperature responsive element 4 moves'the inner valve cylinder 3 to close o ports B and C while opening ports D and E. When this occurs, the preliminarily heated oil enters port A through conduit I5 and flows around the valve cylinder and out through port D into conduits 26 and 24, through the secondary section 20 and thence through conduit 25 to port E whence it is discharged in the central bore of the valve and flows out of the valve through port G to the line 9 running to tank I0. l

After the oil temperature rises and assumes the desired predetermined operating temperature, the thermal operator 4 moves the sleeve 3 to close port D and open port F. In this position, oil enters port A, ows around the sleeve and out through port F, then to the primary core I9 through conduit 24 to the secondary heat exaction of the thermqstatic device 4, the control changer 20, through conduit 25 to port E and thence into the central tubular bore of the valve and through discharge outlet G.

Figure 3 carries the improved lubricating syskrelief valve and be Iby--passed around the control -valve directly'to reservoir i0. While the relief valve 21 has been shown external to the valve, it is obvious that it may be incorporated in the sleeve if so desired so long as it is capable of communication with port A and port G.

The modied systems shown in Figures 7, 8 and 9, together with the modified multi-port sliding control valve illustrated in Figures 10, 11 and 12, are fundamentally the same as the systems and control valve previously described in Figures 1, 2 and 3, and 4, 5 and 6, respectively.

The purpose of these modified systems is to readily control the oil under the conditions of starting and iiightas above described with the added feature of control when it is desired that the oil lead to diierent sections of the oil tank. Under certain conditions, this further control is an'advantage, and to accomplish the same, the control valve i is provided with additional ports H and J. The inner sliding cylinder 3 is also modified at portions 30 and 3|, see particularly Fig.- ures 7, 10, 11 and 12.

The reciprocating control valve in these iigures performs the functions and operations of the valve shown in Figures 4, 5 ando, although instead of allowing the oil to ow through outlet G and return to tank I ll through the single conduit 9, the oil at lower temperatures may flow out of port H, through conduit 32 to one section of the reservoir tank. At a secondpredetermined temperature, see Figure ,12, the-port E will be closed Figures 16 and 17 show a rotary valve -performing the/ same functions as that ,valve shown in Figure 10, the sleeve 2 being rotated instead'of translated to register with the ports. 'Ihe ports are lettered A' toJ', corresponding to those lettered A to J in Figure 10, and perform similar functions. Itis obvious that this valve arrangement may be used in lplace of that shown in Figure 10 in the various diagrams shown.

While the thermal elements 4 have been shown for purposes of illustration as a spiral, the thermai element can be of other well known types such as a bellows, Syl-p'hons or other elements translating temperature changes to motion.

To those skilled inthe art, it will be evident that while the same thermostatic means may control these functions, the predetermined temperatures and routing of the outlet oil may be varied at will'regardless of the sequence of operations of the main valve function.

I claim as my invention: y

The method of controlling oil temperature in a system having an engine, an oil reservoir, primary and secondary heat exchangers, a common conduit leading from the heat exchangers to thereservoir and a thermal-responsive control means in said conduit, that comprises directing the flow of oil from the en'gine to/the reservoir sequentially through each ofthree distinct pathsall of which terminate in said common conduit, by first directing the oil through a -by-pass closed with respect to said heat exchangers in response to a low oil temperature in saidlconduit constituting the rst path, and thereafter rdirecting the oil through s'aid secondary heat exchanger in response to a predetermined higher oil temperature in said conduit constituting the second path, and thereafter directing the oil through saidl primary heat-exand port J opened; whereupon, the oil will flow out through port J, through conduit 33` to a different section of the tank l0. It is to be understood that at intermediate temperatures, or during a. change of temperature, both ports H and J will be open and oil may return to the reservoir through both conduit 32 and 33.

In Figure 9, the modied system of Figure 7 is provided with a pressure relief valve 34 communicating with the inlet port A through conduit 435 and through conduit 36 with line 33 leading to the oil tank l0. However, the relief valve may be joined to the other tank line 32 by conduit 3,1, shown in dotted lines.

Figures 13, 14 and 15 show an arrangement o1 the valve shown in Figure 4 whereby the sleeve, or plug, 3l is rotated instead of translated to register the ports. Ports on this valve have been lettered A', B', C', D', E', F' and G' and perform similar functions to those lettered A, B, C, D, E, F and G, respectively, of the valve shown in Figure 4. Thus, it is apparent that the valve shown in Figure 13 may be used in those circuits where the valve shown in Figure 4 has been used since it performs the same function.

o Number changer 'in,response to an oil temperature in said conduit exceeding said last-named temperature constituting the third path.

LESLIE T. MIILER..

REFERENCES CITED The following references are of record'inithe nie of this patent:

UNTI'ED STATES PATEN'IS FOREIGN PATENTS Country Date Great Britain June 17, 1926 Great Britain June 5, 1930 Great Britain Feb. 23, 1937 Great Britain Nov. 9, 1938 France June 5, 1939 Number 

